Short term biological effects of rewarming hypothermic piglets with 915 MHz microwaves

Before suckling, 14 newborn piglets, weighing <1.25 kg, were dried, weighed, and their rectal temperatures recorded. Rectal temperatures were then reduced to 25 degrees C, to induce hypothermia, by placing the piglets in a 10 degrees C cooling unit. A microwave (MW) generator was programmed to rewarm at a rate of approximately 1.0 degrees C/min, while infrared (IR) rewarming was provided by a 250 W IR heating lamp. Piglets were rewarmed to 38 degrees C and then returned to the sow and their temperatures monitored until 38 degrees C was maintained. Blood samples were taken at birth, after cooling, after rewarming, and when they were killed, 48 h after rewarming. Rewarming time was shorter for MW than IR rewarmed piglets, approximately 10 and 101 min, respectively. Plasma cortisol levels showed no significant differences due to treatment within the 4 sampling times. Cortisol levels between times for each treatment were different. Plasma glucose levels from samples taken at birth, after cooling, and after rewarming were not significantly different between treatment groups. Rewarming treatment did not influence liver glucose or glycogen levels. The percentage area of the adrenal gland zones was not different between the 2 groups. It is concluded that rewarming hypothermic piglets with 915 MHz MW is a safe and efficient method, with no apparent side effects..